Pharmaceutical Suspensions: Size and Stability
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Questions and Answers

What is the typical particle diameter range for most pharmaceutical suspensions?

  • 10-100 pm
  • 50-100 pm
  • 1-10 pm
  • 1-50 pm (correct)

    • Which method is best for producing drug powders with a size of about 10-50 micrometers?

  • Spray-drying
  • Mortar and pestle
  • Micro pulverization (correct)
  • Fluid energy grinding

    • What is a potential issue when reducing particle size too much?

  • Particles may not dissolve
  • Increased drug bioavailability
  • Improved stability of the suspension
  • Formation of a compact cake upon settling (correct)

    • Which particle shape produces a more stable suspension?

    <p>Symmetrical barrel-shaped particles (B)</p> Signup and view all the answers

    Which of the following agents is NOT used to thicken the dispersion medium of a suspension?

    <p>Sodium chloride (B)</p> Signup and view all the answers

    What is the primary function of fluid energy grinding?

    <p>To produce ultra-fine or micronized particles (C)</p> Signup and view all the answers

    Which characteristic of small particles can lead to stability issues in suspensions?

    <p>Their tendency to clump together (B)</p> Signup and view all the answers

    What term describes a loose aggregation of particles held together by weak bonding forces?

    <p>Floc or floccule (B)</p> Signup and view all the answers

    What is one consequence of using fine particles in suspensions?

    <p>They tend to form a compact cake upon settling. (B)</p> Signup and view all the answers

    Which method is specifically used for producing ultra-fine particles for parenteral suspensions?

    <p>Fluid energy grinding (A)</p> Signup and view all the answers

    What is the primary mechanism involved in fluid energy grinding?

    <p>High-speed air stream creating shearing action. (D)</p> Signup and view all the answers

    What is a key advantage of using carboxymethylcellulose in suspensions?

    <p>It thickens the dispersion medium and aids in stabilization. (A)</p> Signup and view all the answers

    In producing pharmaceutical suspensions, why are symmetrical barrel-shaped particles preferred?

    <p>They produce more stable suspensions. (C)</p> Signup and view all the answers

    What is one drawback of using mortar and pestle for particle size reduction?

    <p>It cannot achieve uniformity in particle size. (D)</p> Signup and view all the answers

    Which process is necessary to produce particles under 10 micrometers in diameter?

    <p>Micronizing (A)</p> Signup and view all the answers

    What effect do thickening agents like methylcellulose have on the suspension?

    <p>They increase the viscosity of the dispersion medium. (A)</p> Signup and view all the answers

    Flashcards

    Particle size in pharmaceutical suspensions

    Particle size in pharmaceutical suspensions typically ranges from 1-50 pm (picometers) for suspensions.

    Micropulverization

    A rapid, inexpensive method for creating fine drug powders (10-50 µm).

    Fluid energy grinding

    A process, sometimes called jet milling or micronizing, used to produce particles smaller than 10 µm via high-velocity compressed air.

    Spray-drying

    A method to produce extremely small particles by rapidly drying a drug solution using warmed air.

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    Floc/Floccule formation

    A method to prevent particle cohesion by creating a less rigid aggregation of particles with weak bonding.

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    Suspensoid particle shape

    Particle shape (e.g., barrel vs. needle-shaped) affects stability and tendency to cake.

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    Particle size reduction effects on settling

    Reducing particle size slows settling, but creates a risk of compaction.

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    Thickeners (in suspensions)

    Substances (like carboxymethylcellulose, methylcellulose, etc.) used to thicken the liquid medium and suspend particles.

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    Particle size in suspensions

    The diameter of particles in most pharmaceutical suspensions typically falls between 1-50 micrometers (µm).

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    Particle shape and stability

    The shape of particles in a suspension affects its stability. Symmetrical shapes, like barrels, tend to form more stable suspensions than needle-shaped particles.

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    Floc formation

    The intentional creation of loose particle clusters (floccules) in a suspension to prevent compact settling and caking.

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    Impact of particle size on settling

    Reducing particle size slows down settling, but can lead to particles forming a compact cake at the bottom if they are too fine.

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    Study Notes

    Pharmaceutical Suspensions: Particle Size and Stability

    • Particle Size Range: Most pharmaceutical suspensions contain particles between 1 and 50 µm.

    • Micro Pulverization: A rapid and inexpensive method to produce fine drug powders (10-50 µm) using high-speed mills. Suitable for oral and topical suspensions.

    • Fluid Energy Grinding/Jet Milling/ Micronizing: Used to create particles smaller than 10 µm. High-velocity compressed air shears particles in a confined space, creating micronized particles. Suitable for parenteral or ophthalmic suspensions.

    • Spray Drying: Produces extremely small particles. A solution is sprayed into a cone-shaped apparatus where heated, dry air rapidly dries the solution. Mortar and pestle methods can't achieve this level of particle size control.

    • Particle Size and Settling: Reducing particle size slows settling but extremely fine particles can form a compact cake. Avoiding excessive fineness is important.

    • Particle Shape and Stability: Particle shape affects caking and stability. For example, symmetrical barrel-shaped particles are more stable than needle-shaped ones.

    • Flocculation: Intentional formation of a loose aggregation (floc) of particles, held together by weak bonds, prevents rigid cohesion.

    • Suspension Thickening Agents: Substances like carboxymethylcellulose, methylcellulose, microcrystalline cellulose, polyvinyl pyrrolidone, xanthan gum, and bentonite thicken the dispersion medium to aid in suspending the particles.

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    Description

    Explore the crucial aspects of pharmaceutical suspensions, focusing on particle size and stability techniques. Learn about methods like micro pulverization, jet milling, and spray drying, and their impact on suspension performance. Understand how particle size influences settling properties and overall effectiveness in formulations.

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